Field of the Invention
The present invention relates to an automatic method to repair circuit shorts and near-shorts present in narrow bridges or remnants of bridges between circuit lines. By applying a voltage across a pair of lines, certain electrical phenomena take place at the area of the short or near-short. The electrical phenomena thus generated induce a localized etching in either a gas-phase or liquid-phase medium depending upon which embodiment is used.
In particular, the invention comprises two embodiments:
The first embodiment covers the repair of a near-short circuit which includes two methods: (A) A dry method in a gas chamber where a high voltage (i.e. 100-500 V) generates a localized discharge (micro-plasma) at the narrowest point of the gap between the two lines that generates reactive ions that etch away the unwanted metal and make the gap wider; and (B) a wet method using an etching solution whose etching rate depends sharply on temperature or electric current or both, and applying a certain voltage between these two lines so that a high field concentration is created at the narrowest point of the gap between the two lines which in turn generates an area of very high current concentration that etches away the unwanted metal and makes the gap wider.
The second embodiment covers the repair of a short circuit, which includes two methods: (A) A dry method using a gas phase which utilizes a temperature dependent chemical reaction; and (B) A wet method using a liquid phase which utilizes a temperature dependent wet etching reaction.
The repair of the short is a self-intensifying process that accelerates automatically until the bridge is broken, and then it stops automatically. At that point, the gap is in general too narrow. It is then treated as a near-short as described in the first embodiment.